Microwave electronic parts come in modular form in which a number of electronic circuits and components are housed within the walls of a module, which is usually made of metal, plated typically, with gold.
Inside the housing are located a number of electronic components which can be microwave integrated circuits or individual components, which are typically attached to a substrate using epoxies, most notably silver epoxies, which soften at various temperatures. It is characteristic of these epoxies that they have glass transition temperature, above which they soften and are more readily sheared.
These modules, which range in cost between $3,000.00 and $100,000.00, are costly enough such that reworking the modules due to failed components is a priority. In the past, reworking involved the utilization of a chisel and a ball peen hammer in which the faulty component was chiseled off of the substrate. This process took between 30 minutes and a number of hours depending on the complexity of the circuit and the close tolerances involved. Oftentimes rework resulted in collateral damage in which nearby components were damaged by the chiseling and the debris caused by hammering of the chisel into the circuit. The result in some cases is that not only was the originally damaged component removed, but it was oftentimes necessary to remove large portions of the microwave circuitry due to the damage caused by the chiseling in the attempt to rework the module to remove and replace the failed components.
Note that in general, silver epoxy is used for the attachment of semiconductor devices to aluminum and titanium housings and that it was found that a four-ounce ball peen hammer with miniature scalpel blades having chisel-type surgical tips was the preferable way to rework these microwave components.
Note that an additional problem with regard to the removal of the components is the fact that oftentimes the component to be removed is adjacent an isolation wall such that getting a chisel behind the component is often impeded by the presence of the isolation wall.
In a typical prior operation, the module is fixtured in a small vise and positioned underneath a microscope to allow the operator to target or identify the device needing rework. Thereafter, while working under the microscope, the operator would position her chisel on the device and hack the device into thousands of small pieces, which would scatter and litter about the module. Note that the vice was manually positioned and held in place with one hand of the operator, who would hold the vise and the chisel in the same hand to maintain the device in position under the microscope while the operation was performed.
This of course is not only an awkward way of removing the damaged device but also requires great skill in order to be able to hold the chisel and the vise with one hand and hold the hammer in the other hand, all the while peering through the microscope.
Very often the collateral damage not only resulted in the destruction of adjacent devices but also damage to the underlying substrate or housing, which could be gouged severely during the chiseling operation. In such cases it is necessary to scrap the housing and module altogether. Thus, during the rework process it was oftentimes the case that the modules were so severely damaged that the $3,000.00 to $100,000.00 module needed to be replaced with a new module.
It was therefore readily apparent that there was a need for a device that was more surgical in nature, that would result in minimal collateral damage, and would result in a removal of the identified component, oftentimes in seconds as opposed to 30 minutes or more.